Dynamic cranial nerve stimulation based on brain state determination from cardiac data

Abstract

A method of treating a medical condition in a patient using an implantable medical device, comprising providing an electrical signal generator; providing at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; sensing cardiac data of the patient; determining at least a first cardiac parameter based upon said cardiac data; setting at least a first value; declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting the at least a first value. Also, a computer readable program storage device encoded with instructions that, when executed by a computer, performs the method. In addition, the implantable medical device used in the method.

What is claimed is: 
     
       1. A medical device comprising:
 a cardiac data sensing module operable to sense cardiac data; 
 a non-cardiac data sensing module operable to sense non-cardiac data; 
 a value setting module operable to set:
 a first cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module; and 
 a first non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac data sensing module; 
 
 a cardiac parameter detection module operable to determine a first cardiac parameter based upon sensed data from the cardiac sensing module; 
 a non-cardiac parameter detection module operable to determine a first non-cardiac parameter based upon sensed data from the non-cardiac sensing module; 
 an unstable brain state declaration module operable to declare a seizure when the first cardiac parameter exceeds the first cardiac threshold value or the first non-cardiac parameter exceeds the first non-cardiac threshold value. 
 
     
     
       2. The medical device of  claim 1 , wherein:
 the value setting module is further operable to set a second cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module; 
 the cardiac parameter detection module is further operable to determine a second cardiac parameter based upon sensed data from the cardiac sensing module; and 
 the unstable brain state declaration module is further operable to declare a seizure when the second cardiac parameter exceeds the second cardiac threshold value. 
 
     
     
       3. The medical device of  claim 1 , wherein:
 the value setting module is further operable to set a second non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac data sensing module; 
 the non-cardiac parameter detection module is further operable to determine a second non-cardiac parameter based upon sensed data from the non-cardiac sensing module; and 
 the unstable brain state declaration module is further operable to declare a seizure when the second non-cardiac parameter exceeds the second non-cardiac threshold value. 
 
     
     
       4. The medical device of  claim 1 , further comprising:
 a second non-cardiac data sensing module operable to sense a second non-cardiac data; 
 the value setting module is further operable to set a second non-cardiac threshold value based upon sensed non-cardiac data from the second non-cardiac data sensing module; 
 the non-cardiac parameter detection module is further operable to determine a second non-cardiac parameter based upon sensed data from the second non-cardiac sensing module; and 
 the unstable brain state declaration module operable to declare a seizure when the second non-cardiac parameter exceeds the second non-cardiac threshold value. 
 
     
     
       5. The medical device of  claim 1 , wherein:
 the value setting module is further operable to apply a weighting to the first cardiac threshold value and the first non-cardiac threshold value; and 
 the unstable brain state declaration module is operable to utilize the weighting in declaring a seizure. 
 
     
     
       6. The medical device of  claim 1 , wherein the value setting module is further operable to adjust a threshold value in response to a user request to adjust the threshold value. 
     
     
       7. The medical device of  claim 1 , wherein the value setting module is further operable to adjust each threshold value to render the unstable brain state declaration module less likely to declare a seizure. 
     
     
       8. The medical device of  claim 1 , wherein the value setting module is further operable to adjust each threshold value to render the unstable brain state declaration module more likely to declare a seizure. 
     
     
       9. The medical device of  claim 1 , wherein the first cardiac parameter is selected from the group comprising:
 an instantaneous heart rate; 
 a moving average heart rate over a predetermined time period; 
 a ratio of a first moving average heart rate over a first predetermined time period and a second moving average heart rate over a second predetermined time period; 
 a rate of change of a heart rate; 
 an elevation of an instantaneous heart rate above a baseline heart rate; 
 a duration of an elevation of a heart rate above a baseline heart rate; 
 a depression of a heart rate below a baseline heart; 
 a duration of an elevation of a first moving average heart rate over a second moving average heart rate; 
 an R-R interval; 
 a PR segment interval; 
 a PQ segment interval; 
 a QRS interval; 
 an ST segment interval; 
 a statistical analysis heart parameter; 
 a spectral analysis heart parameter; 
 a fractal analysis heart parameter; 
 an interbeat interval; 
 an amplitude or a magnitude of the P wave, Q wave, R wave, S wave, T wave, U wave; 
 a change in amplitude or a magnitude of a wave; and 
 a rate of change inn amplitude or a magnitude of a wave. 
 
     
     
       10. The medical device of  claim 1 , wherein the first non-cardiac parameter is selected from the group comprising:
 an activity level; 
 an output of an accelerometer; 
 a catamenial cycle; 
 a time of day; 
 an indicator of a sleep state; 
 an inclination of a body; 
 a pupil dilation; 
 a body temperature; 
 a blood pressure; and 
 an electroencephalogram (EEG). 
 
     
     
       11. The device of  claim 1 , wherein the value setting module is operable to dynamically adjust the first cardiac threshold value based upon sensed cardiac data from the cardiac sensing module or the first non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac sensing module. 
     
     
       12. The medical device of  claim 1 , further comprising a memory that stores a timestamp associated with a declaration of a seizure. 
     
     
       13. The medical device of  claim 12 , wherein the value setting module is further configured to adjust a threshold value based upon the timestamp at which a seizure is declared. 
     
     
       14. The medical device of  claim 12 , wherein the value setting module is further configured to:
 perform an analysis of a log of times at which a seizure was declared to determine a first period when an increased frequency of seizure declarations are likely to occur; and 
 adjust the first cardiac threshold value or the first non-cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure during the first period. 
 
     
     
       15. The medical device of  claim 1 , wherein the medical device comprises an implantable medical device (IMD). 
     
     
       16. A medical device comprising:
 a cardiac data sensing module operable to sense cardiac data; 
 a value setting module operable to set:
 a first cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module; and 
 a second cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module; 
 a cardiac parameter detection module operable to determine: 
 a first cardiac parameter based upon sensed data from the cardiac sensing module; and 
 a second cardiac parameter based upon sensed data from the cardiac sensing module; 
 
 an unstable brain state declaration module operable to declare a seizure when the first cardiac parameter exceeds the first cardiac threshold value or the second cardiac parameter exceeds the second cardiac threshold value. 
 
     
     
       17. The medical device of  claim 16 , wherein:
 the value setting module is further operable to apply a weighting to the first cardiac threshold value and the second cardiac threshold value; and 
 the unstable brain state declaration module is operable to utilize the weighting in declaring a seizure. 
 
     
     
       18. The medical device of  claim 16 , further comprising a memory that stores a timestamp associated with a declaration of a seizure. 
     
     
       19. The medical device of  claim 18 , wherein the value setting module is further configured to:
 perform an analysis of a log of times at which a seizure was declared to determine a first period when an increased frequency of seizure declarations are likely to occur; and 
 adjust the first cardiac threshold value or second cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure during the first period. 
 
     
     
       20. The medical device of  claim 16 , wherein the value setting module is operable to dynamically adjust the first cardiac threshold value or the second cardiac threshold value in response to sensed cardiac data from the cardiac sensing module. 
     
     
       21. A method of declaring an unstable brain state using a medical device, comprising:
 sensing cardiac data; 
 sensing non-cardiac data; 
 setting a first cardiac threshold value based upon the sensed cardiac data; 
 setting a first non-cardiac threshold value based upon the sensed non-cardiac data; 
 determining a first cardiac parameter based upon the sensed cardiac data; 
 determining a first non-cardiac parameter based upon the sensed non-cardiac data; and 
 declaring a seizure when the first cardiac parameter exceeds the first cardiac threshold value or the first non-cardiac parameter exceeds the first non-cardiac threshold value.